Cardiac index, left ventricular longitudinal systolic function and atrialised right ventricle size affect exercise capacity in adults with Ebsteins anomaly

Abstract

Background: Small and squashed left ventricular (LV) compressed by markedly enlarged atrialised RV may have some influence on exercise capacity; however, there is no detailed study of the LV in a large cohort of adults with Ebstein's anomaly. Left heart haemodynamic changes including cardiac output and longitudinal LV function may be sensitive in detecting early myocardial damage or ventricular interaction in adults with Ebstein's anomaly. Methods: We enrolled 71 consecutive adults (age 37.0±13.6 years, range 18 – 82 years, 36 males) with Ebstein's anomaly who underwent cardiac magnetic resonance (CMR) between Jan 2004 and Dec 2011. All of them did not undergo any surgery. Bi-atrial and -ventricular size and longitudinal function, and cardiac output were analysed using CMR and two dimensional echocardiogram. We also assessed brain natriuretic peptide (BNP) and exercise capacity using cardiopulmonary exercise test (CPET). Results: Thirteen patients (18.3%) fulfilled the criteria of LV non-compaction. Mean cardiac index (CI) was 2.82±0.70 L/min/m2; mean LV end-diastolic volume index (EDVi) of 79.8±21.8 ml/m2; mean LV end-systolic volume index (ESVi) of 37.2±14.3 ml/m2; mean LV ejection fraction (EF) of 54.7±6.6%; mean LV global longitudinal strain of 15.1±3.5%. The median of mean peak oxygen uptake (peak VO2) of the predicted value in CPET was 64%. We defined peak VO2 of the predicted value<64% as significantly reduced exercise capacity (32 patients, 45.1%). On univariate logistic regression analysis, CI (Odds ratio 0.41 per 1L/min/m2, P=0.045), maximum atrialised right ventricular (RV) volume index in 4 chamber view (Odds ratio per 1cm2/m2, P=0.046), LV global longitudinal strain (Odds ratio 1.25 per 1%unit, P=0.01) were related to exercise capacity. On multivariate analysis, CI and LV global longitudinal strain were significantly related to exercise intolerance. Furthermore, there was significant correlation with LVEF and RVEF (P<0.0001, R=0.60), suggesting ventricular interaction. Conclusions: Cardiac index and LV longitudinal dysfunction are associated with exercise intolerance as well as atrialised RV volumes in adults with Ebstein's anomaly. Furthermore, there is obvious ventricular interaction which has great influence on exercise capacity. Considering the potential prognostic value of LV dysfunction and exercise intolerance in Ebstein's anomaly, left sided meticulous assessments should be regarded as a useful adjunct to potential outcome information in this challenging population.